20hp chrysler not cooling good

[kprey73]

I have an old 1969 chrysler 20hp outboard that was sitting for a couple years, I put a new water impeller in it now it cools good at slow speeds but at higher speeds the motor gets hot. the impeller housing looks good and the tube going from housing to motor is clear.

any help would be great....

thanks much

keith

 

[eurolarva]

Re: 20hp chrysler not cooling good

Did you replace the impeller or someone else? Was the impeller key in the drive shaft? When installing the impeller it is important the vanes are going the correct direction. To install you want the impeller key in the drive shaft. Place impeller on drive shaft key. Put water pump on impeller. Slowly turn the drive shaft clockwise while pushing down firm on the water pump till it houses completely. Other thing is to make sure the water tube on top is in the grommet under the power head. It is possible to miss this hole when putting it back together. Was old impeller destroyed or was it intact when you replaced it?

 

[kprey73]

Re: 20hp chrysler not cooling good

yes I replaced the impeller I made sure the key was in place, the tube looks to be in the grommet on top, could it be possible the grommet is bad - not seating on the tube correctly? the old impeller was intact yet but getting dry rotted.
thanks for the reply

keith

 

[eurolarva]

Re: 20hp chrysler not cooling good

If the grommet is shot it is a pain to replace. I am pretty sure the only way to get to it is to remove the powerhead and the kingpin. If the motor has one you could try and remove the thermostat and test run with it out. If the performance is better then replace it. Chances are the Thermostat has never been replaced. This can be an issue due to the age. Screws on these motors tend to fuse to any metal around them. Just removing the thermostat cover you run the risk of breaking the screws.